wide band ring sizing troubles

[Elizabeth]

Hello all,

I am having some problems with sizing metal for making wider ring band.

I've been using the formula of multiplying the thickness of the metal by 3 and then adding it to the circumference, plus 1-2mm for end straightening. This seems to work fine for thin rings of about 1.5mm but when I did exactly the same thing for a wider band (4mm) it ended up multiple sizes too big (an attempted size U ended up a massive size 1 - 6 sizes too big)!

I suspect perhaps hammering a wide ring on a tapered mandrel is stretching as it's being hammered? Is there any other tool I should be using to round a wide ring (i.e. a tool that's not tapered) or is there some other solution?

Still a newbie so apologies if there is something obviousl I'm missing here! Grateful for any help with this.

[ps_bond]

Not sure I quite follow the reason you're adding 2mm? I recently made a ring in 8x2mm silver using the formula pi*(diameter + thickness) and it came out the right size.

If you're using a steel hammer on a ring mandrel then there's a good chance you'll stretch it; I use a rawhide or UHMWPE mallet (yes, I can tell the difference - just depends which is closer) to finish rounding rings, flipping them over to even it out from both ends.

[Elizabeth]

Hi Peter,
Thanks for reply. I'm using a rawhide mallet and fliping it over to even it out so doesn't seem that's the issue.
I'd been told to add 1-2mm to calculation to allow for straightening the ends of the silver before making the ring, but actually I only added 1mm on the one I described anyway so that doesn't account for the massive size increase either.
It seems the mystery continues....

[ps_bond]

Do you have a record of the measurements you used? Just to cross-check.

[CJ57]

It was my understanding that it is Pi plus the metal thickness only

[Elizabeth]

Hi, sure :
Attempting to make a U size (62.7mm) ring using 4mm wide/1.3mm thick silver wire:
So I did (1.3 x 3) + 62.7 + 1mm = 67.6, rounded up = 68mm length of metal.

[ps_bond]

My charts list U as 62.89 (20.02 diameter); pi * 1.3 + 62.89 = 66.97mm (67 nears as makes no difference).
I still don't follow the need to add on 1mm... If anything, it's preferable to make a ring fractionally small and stretch it.

Can't see how that would land you 6 sizes off - 1, yes, but not 6! Z+1 would need just over 74mm of metal.

[Elizabeth]

Yeah, I know, makes no sense even with the unnecessary extra 1mm. :confused:

[Dennis]

Dear Elizabeth,
Most people take the size of wide rings to be half way between the two edges on a ring stick. However when using expensive metal, it is worth making it in brass or copper first to verify the size.

As far as the length of metal is concerned, please have a look at Andrew Berry here and use the maths only a guide.

https://www.youtube.com/watch?v=xaU5acww9gc Dennis.

[Elizabeth]

Thanks Dennis, yes, have seen the Andrew Berry video and it does look a good method, I will give it a try. Out of interest, which method/tools do you use for bending?
The only thing that puts me off is the extra metal cost if working in something expensive - an extra 10mm (5mm on each side) in silver isn't too bad but would be quite a lot in gold.

[Dennis]

For bending, I use a ring bending tool as below, with a strip of leather inserted to protect the outer surface from marks (fiddly but important). It will bend thick metal with little effort and also serve to press the ends together.
Tools n Tools have some moderately priced ones made in India.
When bending short pieces of stout wire, remember to bend both ends first and then the middle.

I aim to have the ring approximately one English size too small, and then gently stretch it to size with my ring stretcher. No bashing and no damage. Dennis

[Elizabeth]

Thanks Dennis, that's very helpful. It does sound like a good method. Do you do the same process for thinner rings aswell?

[Elizabeth]

Oh - I've just realised where I was going wrong before:
I just measured a second 69mm length of silver that I had ordered to make another version of the first ring that went wrong. It measures 73mm!! #-o
Lesson now learnt to always measure what I've been sent before starting!
Thanks everyone for your patience and help. This has also led me to think about trying the other method aswell, so always good to learn something new.

[ps_bond]

Result! Measure twice, cut once?
(and skip the extra 1mm!)

[Dennis]

Thanks Dennis, that's very helpful. It does sound like a good method. Do you do the same process for thinner rings aswell?

Yes, that is what I do for all rings, except that with silver when I have some stock in hand, I make a ring on the end of a length of wire just like winding a jump ring.
Push it up a ring stick until it reaches the size required (one size below target), and mark where to cut with a water proof pen.
Once soldered it can be stretched to size, with very little loss of thickness, but it ends up well hardened and rounded.
There are no hammer marks and only a few shiny spots on the inside, easily removed with Scotchbrite. Dennis.

[Elizabeth]

Result! Measure twice, cut once?
(and skip the extra 1mm!)

Yes indeed!

[Elizabeth]

Yes, that is what I do for all rings, except that with silver when I have some stock in hand, I make a ring on the end of a length of wire just like winding a jump ring.
Push it up a ring stick until it reaches the size required (one size below target), and mark where to cut with a water proof pen.
Once soldered it can be stretched to size, with very little loss of thickness, but it ends up well hardened and rounded.
There are no hammer marks and only a few shiny spots on the inside, easily removed with Scotchbrite. Dennis.

Thanks for that. Do you find it expensive when making with gold because of the excess needed to wrap around?

[Dennis]

Thanks for that. Do you find it expensive when making with gold because of the excess needed to wrap around?

No, for gold, I would use the length needed minus about 1.00mm, to allow for expansion.

Some use the formula: length= 3.14 x (diameter+ Thickness). Others use a table http://mordent.com/toolsapps/
If using English sizes, make sure the letters are upper case. Dennis

[china]

Dennis I checked out the link just for my interest it does not work, may just be me thought I would let know in case it it does not work for anyone

[Elizabeth]

No, for gold, I would use the length needed minus about 1.00mm, to allow for expansion.

Some use the formula: length= 3.14 x (diameter+ Thickness). Others use a table http://mordent.com/toolsapps/
If using English sizes, make sure the letters are upper case. Dennis

Do you not add the extra 5mm on each side for bending it that Andrew Berry talks about in the video?
That's the bit that was putting me off the technique as it would add considerable expense.

[Dennis]

Do you not add the extra 5mm on each side for bending it that Andrew Berry talks about in the video?
That's the bit that was putting me off the technique as it would add considerable expense.

No, provided you bend the ends first the bending tool can cope without any extra. Dennis.

[Dennis]

Dennis I checked out the link just for my interest it does not work, may just be me thought I would let know in case it it does not work for anyone

That's strange Bob: it works from here, but if you google: http://mordent.com/toolsapps/ it should come up. That said, it although it has been popular on the forum, I just use callipers on my ring stick and my desk calculator which has Pi. Dennis.

[Elizabeth]

No, provided you bend the ends first the bending tool can cope without any extra. Dennis.

Oh that's great. So do you just file the ends and then bend round, no sawing through?

[Dennis]

No, sawing through heavy ends can go wonky, so in this instance I just lightly file the ends, using a filing block also known as a chenier clamp, which makes sure they are perfect.

Obviously you don't absolutely need this tool, bottom right of my picture, but I like it. Dennis.

[china]

Dennis I tried it again and all seems well ( internet gremlins having fun)

[Elizabeth]

No, sawing through heavy ends can go wonky, so in this instance I just lightly file the ends, using a filing block also known as a chenier clamp, which makes sure they are perfect.

Obviously you don't absolutely need this tool, bottom right of my picture, but I like it. Dennis.

Ah thanks Dennis, that's really helpful. I also have that clamp and think it's brilliant. Just ordered a ring stretcher and some ring bending pliers so will give it a go.

[Dennis]

Ok, last word:

Go slowly with the ring stretcher and keep checking on your ring stick, because you can easily pass the mark.
Rotate the ring a little at each press, to ensure it ends up round, not five sided.

Practice with copper, or a scrap ring first to get the hang of it. Dennis.

[Elizabeth]

Ok, last word:

Go slowly with the ring stretcher and keep checking on your ring stick, because you can easily pass the mark.
Rotate the ring a little at each press, to ensure it ends up round, not five sided.

Practice with copper, or a scrap ring first to get the hang of it. Dennis.

Thanks very much Dennis, will do.